Processing aid, vinyl chloride resin composition containing the same, and process for producing molded article with the same

ABSTRACT

The present invention provides a processing aid that reduces ungelled products and flow marks generated on a sheet, and improves releasability of the sheet from the metallic surface of a roll, with the processing aid comprising: 
     a copolymer (A) obtained by copolymerizing a monomer mixture comprising 70 to 90% by weight of methyl methacrylate, 10 to 30% by weight of acrylate or methacrylate other than methyl methacryrate and a different type of monomer capable of being copolymerized with those monomers; and 
     a copolymer (B) obtained by copolymerizing a monomer mixture comprising at least 30% by weight of methyl methacrylate and a monomer having as constitutional units at least one type selected from methacrylates other than methyl methacrylate, acrylates, aromatic alkenyl compounds and other monomers.

TECHNICAL FIELD

The present invention relates to a processing aid for vinyl chloridebased resin and a vinyl chloride based resin composition using the same,and more particularly to a processing aid for calender molding, whichprovides an effect of promoting gelation during calender molding ofvinyl chloride based resin without giving damages to properties that thevinyl chloride based resin originally has, and can eliminate generationof ungelled products of a calendar sheet that are problematic incalender molding and flow marks that can hardly be eliminated byconventional processing aids, and also improves releasability of sheetsfrom roll metal surfaces during calender molding, a vinyl chloride basedresin composition for calender molding using the same, and a method ofproducing moldings using the same.

BACKGROUND ART

Vinyl chloride based resin are excellent in various kinds of physicalproperties and chemical properties, and are widely used for variouskinds of products such as films, sheets, bottles, building materials,floor materials and wire coatings. However, for vinyl chloride basedresin, the molding range is limited because the molding temperature isclose to the thermal cracking temperature, and it is difficult to obtainuniform molten material from powder quickly by kneading operations andthe like because the speed of gelation is low, often resulting indeteriorated surfaces of molten material. Many techniques aiming atovercoming these problems are known. They include, for example, additionof plasticizers, and copolymerization of vinyl chloride resin with othermonomer. However, addition of plasticizers causes problems such asvaporization and escaping of plasticizers, and may compromise physicalproperties of final moldings. In the method using coplymerization ofvinyl chloride resin with other monomer, the amount of monomer to becopolymerized should be limited for carrying out the copolymerizationwithout giving no damages to the original properties of vinyl chlorideresin, and if the amount thereof is too large, the physical propertiesof final moldings may be deteriorated as in the case of addition ofplaticizers.

On the other hand, for the purpose of improving so called processabilitysuch that gelation of resin is promoted during molding of vinylchloride, the smoothness of the surface of the moldings is maintainedeven in long time molding, and the gloss of the surface Is keptconstant, some of copolymers compatible with vinyl chloride resin areconsidered as processing aids, and method of blending these copolymersas processing aids. All of them are copolymers having methylmethacrylate as a main component. For vinyl chloride resins with thesecopolymers blended therein, the gelation speed is high and secondaryprocessability is significantly improved, but there are disadvantagesleading to degradation of commercial values of final moldings, forexample generation of ungelled products due to their poor dispersion.

Then, as a method for enhancing the gelation speed of vinyl chlorideresin, and curbing the generation of ungelled products due to poordispersion of added processing aids, a vinyl chloride based resincomposition is proposed in which a multi-stage copolymer comprisingpolymethyl methacrylate and a copolymer of a monomer superior in amountselected from the group consisting of acrylates and methacrylates otherthan methylmethacrylate and methylmethacrylate inferior in amount, or apolymer mixture with these polymers blended in latex conditions, or amulti-stage polymer comprising a copolymer obtained from methylmethacrylate superior in amount and a monomer inferior in amountselected from the group consisting of acrylates and methacrylates otherthan methyl methacrylate, and a copolymer obtained from methylmethacrylate inferior in amount and a monomer superior in amountselected from the group of consisting of acrylates and methacrylatesother than methyl methacrylate, or a polymer mixture with these polymersblended in latex conditions are blended as processing aids (JapanesePatent Publication No. 52-49020, Japanese Patent Publication No.53-2898).

In addition, it is also proposed that a multi-stage polymer with thediameter of particles of latex defined is used when a processing aid isprepared by emulsion polymerization (See Japanese Patent No. 2515014).

Vinyl chloride based resin compositions with a processing aid comprisingsuch specific copolymers described in the above publication haveimproved properties in terms of generation of ungelled products andsecondary processability.

For improving secondary processability while promoting gelation,however, the molecular weight of the processing aid should be large. Forthis reason, the melting viscosity of the resin composition duringmolding is increased, thus rising a disadvantage that flow marks aregenerated on the surface of calendar sheets during calender molding,resulting in degradation of the commercial value of moldings at the sametime.

For the purpose of improving the above described problems, a vinylchloride based resin composition is proposed in which a copolymercomprising methyl methacrylate and specific methacrylate is blended as aprocessing aid (See Japanese Patent No. 2813248).

On the other hand, the copolymer having methyl methacrylate as a maincomponent also has a disadvantage that its stickiness to metal surfacesis essentially high, which leads to poor releasability of sheets fromthe metallic surface of a roll.

For the purpose of improving the releasability of sheets from themetallic surface of a roll in calender molding, use of various kinds oflubricants in combination is considered, but upper limits should beimposed on the amount of these lubricants to be used in terms ofmaintenance of the physical properties of vinyl chloride based resincompositions, and even within the proper range of usage amounts, lack oflong-term releasability of sheets, the bloom to the surface of a finalmoldings or deposition of lubricants to the metallic surface of the rollduring calender molding is caused, and thus it cannot provide auniversal solution.

In recent years, in calender-molding of vinyl chloride resin,enhancement of production speed to reduce molding time together with thescale-up of molders is promoted in order to improve producibility. Inassociation with the enhancement of the speed of calender molding, alarge number of ungelled products and flow marks are generated on thesheet molded by calender molding, leading to deterioration of appearanceand quality of final moldings, and thus techniques to improve thissituation are required. In addition, techniques to further improvereleasability of sheets from the metallic surface of the roll are alsorequired.

DISCLOSURE OF THE INVENTION

An object of the present invention is to fulfill the above describedrequirements. That is, an object of the present invention is to provide,under a high speed calender molding condition of a vinyl chloride basedresin, a processing aid for calender molding that reduces generation ofungelled products and flow marks on sheets leading to degradation ofcommercial values of final moldings, and improves releasability ofsheets from the metallic surface of a roll, a vinyl chloride basedcomposition for calender molding using the processing aid.

As a result of making vigorous considerations to solve the abovedescribed problems, the inventors have found that a processing aidcomprising two types of polymers different in functionality, namely acopolymer (A) and a copolymer (B) is blended in vinyl chloride resin,thereby making it possible to reduce ungelled products and flow marks incalender-molding, and improve the releasability of sheets from themetallic surface of a roll, and thus completed the present invention.

That is, the gists of the present invention are

(1) a processing aid comprising:

a copolymer (A) whose mean weight molecular weight (Mw) measured withgel permeation chromatography is in the range of from 700,000 to2,000,000, and molecular weight distribution (Mw/Mn) is 3.0 or smaller,which is obtained by copolymerizing a monomer mixture comprising 70 to90% by weight of methyl methacrylate, 10 to 30% by weight of acrylate ormethacrylate other than methyl methacrylate and a different type ofmonomer capable of being copolymerized with those monomers, and

a copolymer (B) whose mean weight molecular weight (Mw) measured withgel permeation chromatography is in the range of from 10,000 to 500,000,which is obtained by copolymerizing a monomer mixture comprising atleast 30% by weight of methyl methacrylate and a monomer having asconstitutional units at least one type selected from methacrylates otherthan methyl methacrylate, acrylates, aromatic alkenyl compounds andother monomers;

(2) a vinyl chloride based resin composition comprising 100 parts byweight of vinyl chloride based resin and 0.1 to 20 parts by weight ofthe processing aid described in the above item (1); and (3) a method ofproducing moldings by calender molding from the vinyl chloride resincomposition described in the above item (2).

The processing aid of the present invention is blended in vinyl chloridebased resin, thereby making it possible to reduce ungelled products andflow marks on sheets in calender molding and improve the releasabilityof sheets from the metallic surface of a roll and thus the industrialvalue of the processing aid is significant.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail below.

The processing aid of the present invention comprises a copolymer (A)whose mean weight molecular weight (Mw) measured with gel permeationchromatography is in the range of from 700,000 to 2,000,000, andmolecular weight distribution (Mw/Mn) is 3.0 or smaller, which isobtained by copolymerizing a monomer mixture comprising 70 to 90% byweight of methyl methacrylate, 10 to 30% by weight of acrylate ormethacrylate other than methyl methacryrate and a different type ofmonomer component capable of being copolymerized with those monomers,and

a copolymer (B) whose mean weight molecular weight (Mw) measured withgel permeation chromatography is in the range of from 10,000 to 500,000,which is obtained by copolymerizing a monomer mixture comprising atleast 30% by weight of methyl methacrylate and a monomer having asconstitutional units at least one type selected from methacrylates otherthan methyl methacrylate, acrylates, aromatic alkenyl compounds andother monomers.

This processing aid will be described in detail below.

The copolymer (A) constituting the processing aid of the presentinvention is a copolymer whose mean weight molecular weight (Mw)measured with gel permeation chromatography is in the range of from700,000 to 2,000,000, and molecular weight distribution (Mw/Mn) is 3.0or smaller, which is obtained by copolymerizing a monomer mixturecomprising 70 to 90% by weight of methyl methacrylate, 10 to 30% byweight of acrylate or methacrylate other than methyl methacryrate and adifferent type of monomer component capable of being copolymerized withthose monomers.

The acrylate has an alkyl group having 1 to 18 carbon atoms, and thealkyl group of the acrylate may be a straight-chain or branched alkylgroup, or a cyclic alkyl group. Specifically, those having astraight-chain alkyl group include methyl acrylate, ethyl acrylate,n-butyl acrylate, lauryl acrylate and stearyl acrylate. Also, thosehaving a branched alkyl group include 2-ethylhexyl acrylate. Inaddition, those having a cyclic alkyl group include cyclohexyl acrylate.If the number of carbon atoms of the alkyl group is larger than 18, thepolymerization property of monomers may be degraded, thus making itdifficult to carry out copolymerization. In addition, the effect ofpromoting gelation of vinyl chloride based resin during calender moldingmay be hindered to cause ungelled products to be generated in the sheet.

The methacrylate other than methyl methacrylate has an alkyl grouphaving 2 to 18 carbon atoms, and the alkyl group of the methacrylate maybe a straight-chain or branched alkyl group, or a cyclic alkyl group.Specifically, those having a straight-chain alkyl group include ethylmethacrylate, n-butyl methacrylate, lauryl methacrylate, stearylmethacrylate and tridecyl methacrylate. Also, those having a branchedalkyl group include i-butyl methacrylate, t-butyl methacrylate and2-ethylhexyl methacrylate. In addition, those having a cyclic alkylgroup include cyclohexyl methacrylate. If the number of carbon atoms ofthe alkyl group is larger than 18, the polymerization property ofmonomers is degraded, thus making it difficult to carry outcopolymerization, which is not preferable. In addition, the effect ofpromoting gelation of vinyl chloride based resin during calender moldingmay be hindered to cause ungelled products to be generated on the sheet.

For the ratio between the methyl methacrylate component and the acrylateor methacrylate component other than methyl methacrylate in the monomercomponent constituting the copolymer (A), the content of the methylmethacrylate component is 70 to 90% by weight, preferably 80 to 90% byweight. The content of the acrylate or methacrylate component other thanmethyl methacrylate is 10 to 30% by weight, preferably 10 to 20% byweight.

If the content of the methyl methacrylate component in the monomercomponent is higher than 90% by weight, dispersibility of the copolymer(A) in vinyl chloride based resin is degraded during calender molding,and ungelled products may be generated. Also, if the content of theacrylate or methacrylate other than methyl methacrylate is higher than30% by weight, compatibility with vinyl chloride resin based resin isdegraded, and the effect of promoting gelation of vinyl chloride basedresin during calender molding may be hindered to cause ungelled productsto be generated in the sheet.

In addition, different types of monomers capable of being copolymerizedwith those monomers include aromatic alkenyl compounds such as styrene,a-methyl styrene, chlorstyrene and vinyl toluene; vinyl cyanidecompounds such as acrylonitrile, methacrylonitrile; vinyl esters such asvinyl acetate; dicarboxylic anhydrides such as maleic anhydride; andpolyfunctional monomers such as divinyl benzene and aryl methacrylate.In the present invention, they may be used alone, or two or more typesmay be used in combination, but these monomer components in the monomercomponent constituting the copolymer (A) are preferably used in thecontent of 3% by weight or lower, more preferably 2% by weight or lowerso as not to deteriorate promotion of gelation of vinyl chloride basedresin, which is an essential function of the processing aid of thepresent invention.

Also, for the mean weight molecular weight (Mw) and molecular weightdistribution (Mw/Mn) of the copolymer (A) measured by gel permeationchromatography, it is preferable that the mean weight molecular weight(Mw) is in the range of from 700,000 to 2,000,000, and the molecularweight distribution (Mw/Mn) is 3.0 or smaller, because they have asignificant influence on the properties as a processing aid for calendermolding.

If the mean weight molecular weight (Mw) of the copolymer (A) is smallerthan 700,000, flow marks on the sheet can be alleviated, but air marksare more likely generated during calender molding. Also, if the meanweight molecular weight (Mw) is larger than 2,000,000, melting viscosityis increased during calender molding, and therefore flow marks are morelikely generated on the sheet.

If the molecular weight distribution (Mw/Mn) of the copolymer (A) islarger than 3.0, low molecular weight components are increased to raisethe possibility of occurrence of exudation, which is not preferable.Allow marks may be influenced in an unfavorable way.

Polymerization methods for obtaining the copolymer (A) include emulsionpolymerization, suspension polymerization and solution polymerization,but emulsion polymerization is most preferably applied.

Here, emulsions capable of being used in emulsion polymerization are notparticularly limited, and known emulsions maybe used. For example,anionic surfactants such as aliphatic esters, alkyl sulfates,alkylbenzene sulfonates, alkyl phosphate salts and dialkylsulfosuccinates; nonionic surfactants such as polyoxyethylene alkylether, polyoxyethylene aliphatic ester, sorbitan aliphatic ester andglycerin aliphatic ester; and cationic surfactants such as alkylamineesters may be used. These emulsions may be used alone or in combination.

Also, when pH of the polymerization system is on the alkali sidedepending on types of emulsions that are used, an appropriatepH-regulator to prevent hydrolysis of alkyl methacrylate and alkylacrylate may be used. As pH-regulators, boric acid-potassiumchloride-potassium hydrate, potassium dihydrogen phosphate-disodiumhydrogen phosphate, boric acid-potassium chloride-potassium carbonate,citric acid-potassium hydrogen citrate, potassium dihydrogenphosphate-boric acid, disodium hydrogen phosphate-citric acid and thelike may be used.

Also, polymerization initiators may be water-soluble or fat-solublesingle system initiators or redox system initiators, and as for examplesof water-soluble initiators, a usual inorganic initiator such aspersulfate may be used alone or in combination with sulfite, bisulfite,thiosulfate and the like as a redox system initiator.

As for examples of oil-soluble initiators, an organic peroxide such ast-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide andlauroyl peroxide, an azo compound or the like may be used alone or incombination with sodium formaldehyde sulfoxylate and the like as a redoxsystem initiator, but oil-soluble initiators should not be limited suchspecific examples.

Also, the mean weight molecular weight (Mw) and molecular weightdistribution (Mw/Mn) of the copolymer (A) can be optionally adjustedwith chain transfer agents such as n-octylmercaptan andt-dodecylmercaptan, and polymerization conditions.

The copolymer (B) constituting the processing aid of the presentinvention together with the copolymer (A) is a copolymer whose meanweight molecular weight (Mw) measured with gel permeation chromatographyis in the range of from 10,000 to 500,000, which is obtained bycopolymerizing a monomer mixture comprising at least 30% by weight ofmethyl methacrylate and a monomer having as constitutional units atleast one type selected from methacrylates other than methylmethacrylate, acrylates, aromatic alkenyl compounds and other monomers,and provides releasability from the metallic surface of the roll tovinyl chloride based resin in calender molding.

The amount of methyl methacrylate to be used is 30 to 55% by weight,preferably 40 to 50% by weight. If the amount of methyl methacrylate tobe used is smaller than 30% by weight, promotion of gelation of vinylchloride based resin may be hindered. In addition, secondary aggregationtends to occur in post processes such as solidification, an hydrationand drying, and thus problems maybe caused in terms of productivity.Also, if the amount is larger than 55% by weight, effects of providingreleasability to vinyl chloride based resin will be compromised.

The methacrylate other than methyl methacrylate has an alkyl grouphaving 2 to 18 carbon atoms, and the alkyl group of the methacrylate maybe a straight-chain or branched alkyl group, or a cyclic alkyl group.Specifically, those having a straight-chain alkyl group include ethylmethacrylate, n-butyl methacrylate, lauryl methacrylate, stearylmethacrylate and tridecyl methacrylate. Also, those having 5 a branchedalkyl group include i-butyl methacrylate, t-butyl methacrylate and2-ethylhexyl methacrylate. In addition, those having a cyclic alkylgroup include cyclohexyl methacrylate.

If the number of carbon atoms of the alkyl group is larger than 18, thepolymerization property is degraded because the polymerization speed isreduced, and problems may be caused in terms of productivity.

The acrylate has an alkyl group having 1 to 18 carbon atoms, and thealkyl group of the acrylate may be a straight-chain or branched alkylgroup, or a cyclic alkyl group. Specifically, those having astraight-chain alkyl group include methyl acrylate, ethyl acrylate,n-butyl acrylate, lauryl acrylate and stearyl acrylate. Also, thosehaving a branched alkyl group include 2-ethylhexyl acrylate. Inaddition, those having a cyclic alkyl group include cyclohexyl acrylate.

If the number of carbon atoms of the alkyl group is larger than 18, thepolymerization property is degraded because the polymerization speed isreduced, and problems may be caused in terms of productivity.

The aromatic alkenyl compounds include styrene, α-methyl styrene,chlorstyrene and vinyl toluene.

Other monomers include vinyl cyanide compounds such as acrylonitrile andmethacrylonitrile, vinyl esters such as vinyl acetate, and dicarboxylicanhydrides such as maleic anhydride.

The amount of these monomers to be used is 45 to 70% by weight,preferably 50 to 60% by weight. If the amount of these monomers to beused is smaller than 45% by weight, the effect of providingreleasability to vinyl chloride based resin will be compromised. Also,if the amount is larger than 70% by weight, the effect of promotinggelation of vinyl chloride based resin may be hindered during calendermolding.

In addition, polyfunctional monomers such as divinyl benzene and arylmethacrylate can also be used, but the amount of these polyfunctionalmonomers to be used in this case is preferably 2% by weight or smaller.

In addition, the mean weight molecular weight (Mw) of the copolymer (B)for use in the present invention, measured with gel permeationchromatography is preferably in the range of from 10,000 to 500,000.

If the mean weight molecular weight of the copolymer (B) is larger than500,000, the effect of providing releasability during calender moldingis significantly compromised. Also, if it is smaller than 10,000, theeffect of providing releasability during calender molding issignificantly compromised.

Polymerization methods for obtaining the copolymer (B) of the presentinvention include emulsion polymerization, suspension polymerization andsolution polymerization, but emulsion polymerization is most preferablyapplied.

Here, emulsions capable of being used in emulsion polymerization are notparticularly limited, and known emulsions may be used. For example,anionic surfactants such as aliphatic esters, alkyl sulfates,alkylbenzene sulfonates, alkyl phosphate salts and dialkylsulfosuccinates; nonionic surfactants such as polyoxyethylene alkylether, polyoxyethylene aliphatic ester, sorbitan aliphatic ester andglycerin aliphatic ester; and cationic surfactants such as alkylamineesters may be used. These emulsions may be used alone or in combination.

Also, when pH of the polymerization system is on the alkali sidedepending on types of emulsions that are used, an appropriatepH-regulator to prevent hydrolysis of alkyl methacrylate andalkylacrylate may be used. As pH-regulators, boric acid-potassiumchloride-potassium hydrate, potassium dihydrogen phosphate-disodiumhydrogen phosphate, boric acid-potassium chloride-potassium carbonate,citric acid-potassium hydrogen citrate, potassium dihydrogenphosphate-boric acid, disodium hydrogen phosphate-citric acid and thelike may be used.

Also, polymerization initiators may be water-soluble or fat-solublesingle system initiators or redox system initiators, and as for examplesof water-soluble initiators, a usual inorganic initiator such aspersulfate may be used alone or in combination with sulfite, bisulfite,thiosulfate and the like as a redox system initiator.

As for examples of oil-soluble initiators, an organic peroxide such ast-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide andlauroyl peroxide, an azo compound or the like may be used alone or incombination with sodium formaldehyde sulfoxylate and the like as a redoxsystem initiator, but oil-soluble initiators should not be limited suchspecific examples.

Also, the mean weight molecular weight of the copolymer (B) can beoptionally adjusted with chain transfer agents such as n-octylmercaptanand t-dodecyl mercaptan, and polymerization conditions.

The processing aid of the present invention is a blend of the copolymer(A) and copolymer (B) obtained as described above, and they are blendedin the ratio of 100 parts by weight of the copolymer (A) to 0.5 to 100parts by weight of the copolymer (B). If the amount of the copolymer (B)blended is smaller than 0.5 parts by weight, good releasability ofsheets from the roll during calender molding, which is a remarkablefeature of the present invention, may not be obtained. Also, if theamount of the copolymer (B) blended is larger than 100 parts by weight,promotion of gelation of vinyl chloride based resin may be hindered.Also, air marks are more likely generated in the sheet during calendermolding, and secondary processability may be degraded.

Also, because the mean weight molecular weight (Mw) and moleculardistribution (Mw/Mn) of the processing aid for calender molding of thepresent invention, measured with gel permeation chromatography has asignificant influence on the properties as a processing aid, it ispreferable that also the mean weight molecular weight of the blend ofthe copolymer (A) and copolymer (B) measured with gel permeationchromatography is in the range of from 700,000 to 2,000,000 and itsmolecular weight distribution is 3.0 or smaller as well, and for theaforesaid blending ratio, the mean weight molecular weight and molecularweight distribution of the blend are preferably in the ranges describedabove.

For implementing the present invention, the copolymer (A) and copolymer(B) are blended by blending each of their latexes in the above describedratio on a solid basis.

For the method of collecting the copolymer (A) and copolymer (B) fromthe blended latex, for example, they may be collected in powder form bysubjecting the latex to acid coagulation or salting out the latex toprecipitate the polymer with an electrolyte of acids such as sulfuricacid, hydrochloric acid and phosphoric acid or salts such as aluminumchloride, calcium chloride, magnesium sulfate, aluminum sulfate andcalcium acetate, followed by filtering, cleaning and drying if they areto be obtained using emulsion polymerization.

Coagulants for use in acid coagulation or salting out are not limitedsuch specific examples, and known coagulants may be used.

Also, known collection methods such as spray drying or freeze drying maybe used.

In addition, there is a method in which the processing aid is obtainedby subsequently blending individual powders of the copolymer (A) andcopolymer (B), but the above described method in which the processingaid is obtained by blending latexes is particularly preferable.

The processing aid of the present invention may be used for variousapplications, for example calender molding, (contour) extrusion molding,injection molding and expansion molding, but it is particularlypreferably used for calender molding.

Vinyl chloride resins for use in the vinyl chloride based resincomposition of the present invention are not particularly limited, andthey include, for example, vinyl chloride homo polyvinyl chloride,after-chlorinated polyvinyl chloride, partially crosslinked polyvinylchloride, or copolymers of vinyl chloride containing no more than 30% byweight of other vinyl compound capable of being copolymerized with vinylchloride and other vinyl compound, and mixtures thereof.

The above described other vinyl compounds capable of being copolymerizedwith the vinyl chloride component are not particularly limited, butspecific examples thereof include aliphatic vinyl esters such as vinylacetate and vinyl propionate; alkyl methacrylates such as methylmethacrylate, ethyl methacrylate and butyl methacrylate: alkyl acrylatessuch as methyl acrylate, ethyl acrylate and butyl acrylate; α-olefinsuch as ethylene, propylene and styrene; alkyl vinyl ethers such asvinyl methyl ether and vinyl butyl ether; and unsaturated carbonic acidssuch as acrylic acid, methacrylic acid and maleic anhydride, oranhydrides thereof, and they may be used alone or in combination of twoor more types thereof.

If the coplymerized amount of the above described other vinyl compoundcapable of being copolymerized is larger than 30% by weight, propertiesspecific of vinyl chloride based resin are signlficantly compromised,which is not preferable. In addition, these vinyl chloride based resinsmay be used alone or in combination of two or more types thereof.

For vinyl chloride based resin for use in the vinyl chloride based resincomposition of the present invention, its mean degree of polymerizationis preferably in the range of from 300 to 5,000, more preferably in therange of from 500 to 3,000. For vinyl chloride based resin of which meandegree of polymerization is lower than 300, calender-molded products mayhave insufficient strength. Also, if the mean degree of polymerizationis larger than 5,000, it is difficult to knead resin sufficiently duringcalender molding, and thus processability may be compromised.

For vinyl chloride based resin for use in the vinyl chloride based resincomposition of the present invention, methods for producing the vinylchloride based resin are not particularly limited, and various knowntechniques such as emulsion polymerization, suspension polymerizationand bulk polymerization may be used.

The vinyl chloride based resin composition of the present invention haspreferably 0.1 to 20 parts by weight, more preferably 0.2 to 10 parts byweight of processing aid blended relative to 100 parts by weight of theabove described vinyl chloride resin. If the blending ratio of theprocessing aid is lower than 0.1 parts by weight, air marks may begenerated on the sheet during calender molding, and releasability of thesheet from the metallic surf ace of the roll may also be degraded. Also,if the blending ratio is larger than 20 parts by weight, thereleasability of the sheet from the metallic surface of the roll isimproved, but effects of alleviating flow marks may be significantlycompromised.

Methods of blending and adding the processing aid in vinyl chloridebased resin are not particularly limited, and known kneading andblending methods may usually be used, and for example, a predeterminedamount of vinyl chloride resin and processing aid are blended using aHenschel mixer, Banbury mixer, ribbon blender, V-type mixer or the like,and the resulting product is processed by a kneader such as a singlespindle extruder, double spindle extruder, pressing kneader or mixingroll, whereby the vinyl chloride based resin composition of theinvention can be obtained. Also, the vinyl chloride based resincomposition may be used in either powder or pellet form.

In the case where the vinyl chloride based resin and processing aid areblended to obtain the vinyl chloride based resin of the presentinvention, various kinds of additives such as a known heat stabilizer,lubricant, processing aid, impact modifier, plasticizer, heat-proofimprover, bulking agent, blowing agent, pigment, ultraviolet stabilizer,anti-fogging agent, anti-fungus agent, antistatic agent, surfactant andflame retardant may be used in combination depending on the purpose, aslong as the effect of the invention is not compromised.

Heat stabilizers include, for example, lead heat stabilizers such astribasic lead sulphate, dibasic lead phosphate, basic lead sulfite, andlead silicate; metallic soap based stabilizers derived from a metal suchas potassium, magnesium, barium, zinc, cadmium and lead, and fatty acidsuch as 2-ethyl hexanoic acid, lauric acid, myristic acid, palmiticacid, stearic acid, isostearic acid, hydroxystearic acid, oleic acid,ricinoleic acid, linoleic acid and behenic acid; organotin basedstabilizers derived from an alkyl group, ester group and apliphaticester, maleate and sulfide compound; composite metal soap basedstabilizers such as a Ba—Zn system, Ca—Zn system, Ba—Ca system, Ca—Mg—Snsystem, Ca—Zn—Sn system, Pb—Sn systemand Pb—Ba—Ca system; metal saltbased stabilizers derived from a metal such as barium and zinc, andusually two or more types of organic acids such as branched fatty acidssuch as 2-ethyl hexanoic acid, isodecanoic acid and trialkyl aceticacid, unsaturated fatty acids such as oleic acid, ricinoleic acid andlinoleic acid, cyclic fatty acids such as naphthenic acid, aromaticacids such as carbolic acid, benzoic acid, salicylic acid andsubstituted derivatives thereof; metal based stabilizers such as metalsalt liquid stabilizers obtained by dissolving the above stabilizers inan organic solvent such as petroleum hydrocarbon, alcohol and glycerinderivatives and blending therein stabilizing aids such as a phosphite,epoxy compound, anti-color agent, transparency improver, lightstabilizer, antioxidant and lubricant; epoxy compounds such as epoxyresin, epoxidized soybean oil, epoxidized vegetable oil and epoxidizedaliphatic alkyl ester; nonmetal stabilizers such as organic phosphitesof which phosphorous is substituted with a alkyl group, aryl group,cycloalkyl group, alkoxyl group or the like, and which have dihydricalcohol such as propylene glycol and aromatic compounds such ashydrochinone and bisphenol A, and they may be used alone or incombination of two or more types thereof.

Lubricants may include, for example, pure hydrocarbon based lubricantssuch as liquid paraffin, natural paraffin, micro wax and syntheticparaffin and low molecular weight polyethylene; halogenated hydrocarbonbased lubricants; fatty acid based lubricants such as higher fatty acidsand oxyfatty acids; amide based lubricants such as fatty amide andbisfatty amide; ester based lubricants such as lower alcohol esters offatty acid, polyalcohol esters of fatty acid such as glyceride,polyglycol esters of fatty acid and fatty alcohol esters of fatty acid(ester wax); and metal soap, fatty alcohol, polyalcohol, polyglycol,polyglycerol, partial esters of fatty acid and polyalcohol, and partialesters of fatty acid and polyglycol or polyglycerol.

In addition, plasticizers include, for example, phthalate basedplasticizers such as dimethyl phthalate, diethyl phthalate, dibutylphthalate, dihexyl phthalate, dinormaloctyl phthalate, 2-ethylhexylphthalate, diisooctyl phthalate, dicapryl phthalate, dinonyl phthalate,diisononyl phthalate, didecyl phthalate, diisodecyl phthalate, diundecylphthalate, dilauryl phthalate, ditridecyl phthalate, dibenzyl phthalate,dicyclohexyl phthalate, butylbenzyl phthalate, octyldecyl phthalate,butyloctyl phthalate, octylbenzyl phthalate, normalhexyl normaldecylphthalate and normaloctyl normaldecyl phthalate; phosphate basedplasticizers such as tricresyl phosphate, tri-2-ethylhexyl phosphate,triphenyl phosphate, 2-ethylhexyldiphenyl phosphate and cresildiphenylphosphate; adipate based plasticizers such as di-2-ethylhexyl adipate,diisodecyl adipate, normaloctyl-normaldecyl adipate,normalheptyl-normalnonyl adipate, diisooctyl adipate, diisonormaloctyladipate, dinormaloctyl adipate and didecyl adipate; sebacate basedplasticizers such as dibutyl sebacate, di-2-ethylhexyl sebacate,diisooctyl sebacate and butylbenzyl sebacate; azelate based plasticizerssuch as di-2-ethylhexyl azelate, dihexyl azelate and diisooctyl azelate;citrate based plasticizers such as triethyl citrate, triethyl acetylcitrate, tributyl citrate, tributyl acetyl citrate and tri-2-ethylhexylacetyl citrate, glycolate based plasticizers such as metylphthalylethylglycolate, ethylphthalylethyl glycolate and butylphthalylbutylglycolate; trimellitate based plasticizers such as tributyltrimellitate, tri-normalhexyl trimellitate, tri-2-ethylhexyltrimellitate, tri-normaloctyl trimellitate, tri-isocutiltrimellitate andtri-isodecyl trimellitate; isomeric phthalate based plasticizers such asdi-2-ethylhexyl isophthalate and di-2-ethylhexyl terephthalate;ricinoleate based plasticizers such as methylacetyl ricinoleate andbutylacetyl ricinoleate; polyester based plasticizers such aspolypropylene adipate, polypropylene sebacate, and modified polyestersthereof; and epoxy based plasticizers such as epoxidized soybean oil,epoxybutyl stearate, epoxy (2-ethylhexyl) stearate, epoxidized linseedoil and 2-ethylhexylepoxy citrate, and they may be used alone or incombination of two or more types thereof.

Impact modifiers may include polybutadiene, polyisoprene,polychloropurene, fluoro rubber, styrene-butadiene copolymer rubber,methyl methacrylate-butadiene-styrene based copolymers, methylmethacrylate-butadiene-styrene based graft copolymers,acrylonitrile-styrene-butadiene based copolymer rubber,acrylonitrile-styrene-butadiene based graft copolymers,styrene-butadiene-styrene block copolymer rubber,styrene-isoprene-styrene copolymer rubber,styrene-ethylene-butylene-styrene copolymer rubber, ethylene-propylenecopolymer rubber, ethylene-propylene-diene copolymer rubber (EPDM),silicone containing acryl based rubber, silicone/acryl composite rubberbased graft copolymers, and silicone based rubber.

For the diene of the ethylene-propylene-diene copolymer rubber (EPDM),1,4-hexanediene, dicyclopentadiene, methylene norbornene, ethylidenenorbornene, propenyl norbornene and the like are used. These impactmodifiers may be used alone or in combination of two or more typesthereof.

For bulking agents, for example, carbonates such as heavy calciumcarbonate, precipitated calcium carbonate and colloid calcium carbonate,minerals such as aluminum hydroxide, magnesium hydroxide, titaniumoxide, clay, mica, talc, wollastonite, zeolite, silica, zinc oxide,magnesium oxide, carbon black, graphite, glass beads, glass fibers,carbon fibers and metal fibers, and organic fibers such as polyamide maybe used, and they may be used alone or in combination of two or moretypes thereof. In addition, a flame retardant such as chlorinatedparaffin, aluminum hydroxide, antimony trioxide and a halogen compound,a fluidity improver, a colorant, an antistatic agent, a surfactant, ananti-fogging agent, and an anti-fungus agent may optionally be blendeddepending on the purpose, as long as the effect of the vinyl chloridebased resin composition of the present invention is not compromised.

Substances that can be blended together with the vinyl chloride basedresin composition of the present invention have been described above,the invention is not limited such specific example.

The vinyl chloride based resin composition can usually be applied toknown molding methods, for example calender molding, extrusion moldingand injection molding to obtain various kinds of moldings, but theeffect of the invention is most enhanced in calender molding.

The present invention will be described further specifically below usingExamples, but the invention should not be limited such Examples.Furthermore, “part” and “%” described in each Example and ComparativeExample mean “part by weight” and “% by weight”, respectively.

In order to demonstrate the outstanding effect of the vinyl chloridebased resin composition of the present invention, tests were carried outfor evaluating roll releasability, flow marks, air marks, gelationproperties and ungelled products.

EXAMPLE 1

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 230parts of ion-exchanged water, 1.0 parts of sodium dioctylsulfosuccinate, 0. 15 parts of potassium persulfate, 85 parts of methylmethacrylate, 15 parts of n-butyl acrylate and 0.0175 parts ofn-octylmercaptan, and then the air in the vessel was replaced withnitrogen again, followed by heating the reaction vessel to 65° C. understirring, heating and stirring for two hours, completing thepolymerization reaction and cooling to obtain a latex of copolymer (A).A part of the obtained latex was added in an aluminum chloride solutionto salt out and coagulate the same, followed by washing and drying toobtain a polymer of copolymer (A). 0.05 g of the obtained polymer ofcopolymer (A) was dissolved in 10 ml of chloroform to measure the meanweight molecular weight (Mw) and the molecular weight distribution(Mw/Mn) using a column (K-806L manufactured by Showa Denko K.K.) in gelpermeation chromatography (LC-10A System manufactured by ShimadzuCorp.), and the mean weight molecular weight (Mw) was 1,100,000 and themolecular weight distribution (Mw/Mn) was 2.0.

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 260parts of ion-exchanged water, 1.5 parts of sodium dioctylsulfosuccinate, 0.2 parts of potassium persulfate, 30 parts of methylmethacrylate and 0.03 parts of n-octylmercaptan, and then the air in thevessel was replaced with nitrogen again, followed by heating thereaction vessel to 65° C. under stirring, and heating and stirring fortwo hours. Subsequently, a mixture of 20 parts of n-butyl methacrylate,30 parts of n-butyl acrylate and 0.5 parts of n-octylmercaptan was addedtherein for one hour, and was stirred for two hours after the mixturewas added. Thereafter, a mixture of 20 parts of methyl methacrylate and0. 05 parts of n-octylmercaptan was added in this reaction system forthirty minutes, and was stirred for two hours, followed by completingthe polymerization reaction and cooling to obtain a latex of copolymer(B).

A part of the obtained latex was added in an aluminum chloride solutionto salt out and coagulate the same, followed by washing and drying toobtain a polymer of copolymer (B). The mean weight molecular weight (Mw)of the obtained copolymer (B) was 220,000.

Then, as a solid matter, 100 parts of latex of copolymer (A) were placedin a reaction vessel provided with a stirrer, and was stirred. 10 partsof latex of copolymer (B) were added therein as a solid matter in tenseconds, followed by stirring for twenty minutes. The obtained latexmixture was added in an aluminum chloride solution to salt out andcoagulate the same, followed by washing, dehydrating and drying toobtain a powdered copolymer mixture. The mean weight molecular weight(Mw) of the copolymer mixture was 1,040,000, and its molecular weightdistribution (Mw/Mn) was 2.4.

This copolymer mixture was subjected to the following valuation tests.

(1) Evaluation of roll releasability: A 6 inch roll (manufactured byKansai Roll Co., Ltd.) was used to knead the mixture, with the kneadingtemperature being 200° C., the roll interval being 0.25 mm and theamount of sample being 100 g, and time until it became difficult torelease the sheet was measured. It was considered that the longer thetime, the better was the releasability of the sheet from the metallicsurface of the roll.

The following blending was used for the resin composition that was usedfor the evaluation of roll releasability.

100 parts of vinyl chloride homopolymer with mean degree ofpolymerization of 800 (TK-800 manufactured by Shin-Etsu Chemical Co.,Ltd.) was blended with 1.7 parts of dibutyl tin mercaptide (T-17MJmanufactured by Katsuta Chemical Industry Co., Ltd.), 1.0 parts ofpolyalcohol aliphatic ester (LoxiolG-16 manufactured by Henkel JapanCo., Ltd.), 6.0 parts of MetabrenC-201A (manufactured by MitsubishiRayon Co., Ltd.) and the copolymer mixture obtained in Examples orComparative Examples, and was blended using a Henschel mixer until theinside temperature reached 120° C., followed by cooling to the roomtemperature to obtain a vinyl chloride based resin composition.

(2) Evaluation of flow marks: The mixture was kneaded for three minutesusing a 6 inch roll (manufactured by Kansai Roll Co., Ltd.), with thekneading temperature being 200° C., the roll interval being 0.25 mm andthe amount of sample being 100 g, to prepare sheets with thickness of0.5 mm, and the amount of flow marks on the sheet was determined byvisual observations and evaluations were made in such a manner that theresults were marked with ◯, Δ and x in descending order ofsatisfactoriness. Here, ◯ means little flow marks, Δ means that flowmarks are so noticeable that problems may be caused from a practicalviewpoint, and x means that a large amount of flow marks are generatedand they are too prominent not to be used practically.

These evaluations were made using the same vinyl chloride based resincomposition as th at used in the evaluation of roll releasability.

(3) Evaluation of air marks: The mixture was kneaded for three minutesusing a 6 inch roll (manufactured by Kansai Roll Co., Ltd.), with thekneading temperature being 200° C., the roll interval being 0.25 mm andthe amount of sample being 100 g, to prepare sheets with thickness of 2mm, and the size and amount of air marks on the sheet were determined byvisual observations, and evaluations were made in such a manner that theresults were marked with ◯, Δ and x in descending order ofsatisfactoriness. Here, ◯ means little air marks, Δ means that air marksare so noticeable that problems may be caused from a practicalviewpoint, and x means that a large amount of air marks are generatedand they are too prominent not to be used practically.

These evaluations were made using the same vinyl chloride based resincomposition as that used in the evaluation of roll releasability.

(4) Evaluation of gelation properties: The maximum torque and time untilthe maximum torque was reached (gelation time) when the mixture waskneaded using Lab Plastomill (manufactured by Toyo Seiki Co., Ltd.),with the temperature being 160° C., the number of revolutions being 30rpm and the loading weight being 53 g, were measured. It was consideredthat the shorter this gelation time, the higher is the gelation speed.

The following blending was used for the resin composition that was usedfor the evaluation of gelation properties.

100 parts of vinyl chloride homopolymer with mean degree ofpolymerization of 800 (TK-800 manufactured by Shin-Etsu Chemical Co.,Ltd.) was blended with 1.1 parts of dibutyl tin mercaptide (T-17MJmanufactured by Katsuta Chemical Industry Co., Ltd.), 0.8 parts ofpolyalcohol aliphatic ester (LoxiolG-16manufactured by Henkel JapanCo.,Ltd.), 0.15parts of polymer ester (LoxiolG-70S manufactured byHenkel Japan Co., Ltd.), 6.0 parts of Metabren C-201A (manufactured byMitsubishi Rayon Co., Ltd.) and the copolymer mixture obtained inExamples or Comparative Examples, and was blended using a Henschel mixeruntil the inside temperature reached 120° C., followed by cooling to theroom temperature to obtain a vinyl chloride based resin composition.

(5) Ungelled products: Using a 20 mm single spindle extruder providedwith a T-die, films with thickness of 0.1 mm were extruded, with thenumber of revolutions of the screw being 40 rpm and the cylindertemperature being 180° C., and the number of ungelled products in afixed area on the film surface was determined by visual observations,and evaluations were made in such a manner that the results were markedwith ∘, Δ and x in descending order of satisfactoriness. Here, ◯ meansthat the result is very good, A means that ungelled products are sonoticeable that problems may be caused from a practical viewpoint, and xmeans that the number of ungelled products is too large not to be usedpractically.

The following blending was used for the resin composition that was usedfor the evaluation of ungelled products.

A vinyl chloride homopolymer with mean degree of polymerization of 700(TK-700 manufactured by Shin-Etsu Chemical Co., Ltd.) was blended with2.0 parts of dibutyl tin mercaptide (T-17MJ manufactured by KatsutaChemical Industry Co., Ltd.), 0.9 parts of polyalcohol aliphatic ester(LoxiolG-16 manufactured by Henkel Japan Co. Ltd.), 0.6 parts of polymerester (LoxiolG-72 manufactured by Henkel Japan Co., Ltd.), 5.0parts ofMetabren C-201A (manufactured by Mitsubishi Rayon Co., Ltd.) and thecopolymer mixture obtained in Examples or Comparative Examples, and wasblended using a Henschel mixer until the inside temperature reached 120°C. followed by cooling to the room temperature to obtain a vinylchloride based resin composition.

EXAMPLE 2

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 150parts of ion-exchanged water, 1.0 parts of sodium dioctylsulfosuccinate, 0.15 parts of potassium persulfate, 80 parts of methylmethacrylate. 4 parts of n-butyl acrylate and 0.018 parts ofn-octylmercaptan, and then the air in the vessel was replaced withnitrogen again, followed by heating the reaction vessel to 65° C. understirring, and heating and stirring for 2.5 hours, followed by adding 10parts of methyl methacrylate and 6 parts of n-butyl acrylate in thereaction vessel over five minutes, and heating and stirring for threehours after they were added, followed by completing the polymerizationreaction and cooling to obtain a latex of copolymer (A). Subsequently, adried product of copolymer (A) was obtained for a part of the obtainedlatex in the same manner as Example 1.

The mean weight molecular weight of the obtained copolymer (A) was1,120,000 and the molecular weight distribution was 2.3.

Air in a reaction vessel provided with a stirrer and a ref lux coolerwas replaced with nitrogen, followed by placing therein a mixture of 150parts of ion-exchanged water, 1.5 parts of sodium dioctylsulfosuccinate, 0.2 parts of potassium persulfate and 30 parts of methylmethacrylate, and then the air in the vessel was replaced with nitrogenagain, followed by heating the reaction vessel to 65° C. under stirring,and heating and stirring for three hours. Subsequently, a mixture of 33parts of styrene, 22 parts of n-butyl acrylate and 0.5 parts ofn-octylmercaptan was added therein for ninety minutes, and was heatedand stirred for two hours after the mixture was added. Thereafter, 15parts of methyl methacrylate were added in this reaction system forthirty minutes, and were heated and stirred for 1.5 hours after theywere added, followed by completing the polymerization reaction andcooling to obtain a latex of copolymer (B). Subsequently, a driedproduct of copolymer (B) was obtained for a part of the obtained latexin the same manner as Example 1.

The mean weight molecular weight (Mw) of the obtained copolymer (B) was400,000.

Latex blending of the copolymer (A) and (B) was carried out in the samemanner as Example 1. Subsequently, the obtained latex mixture wasprocessed in the same manner as Example 1 to obtain a powderedcopolymer. The mean weight molecular weight (Mw) of the obtainedcopolymer was 1,100,000 the molecular weight distribution (Mw/Mn) was2.8.

EXAMPLE 3

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 150parts of ion-exchanged water, 1.5 parts of sodium dioctylsulfosuccinate, 0.2 parts of potassium persulfate, 70 parts of methylmethacrylate, 4 parts of n-butyl acrylate and 0.025 parts ofn-octylmercaptan, and then the air in the vessel was replaced withnitrogen, followed by heating the reaction vessel to 65° C. understirring, and heating and stirring for 2.5 hours, followed by adding amixture of 8 parts of methyl methacrylate, 8 parts of n-butyl acrylateand 0.5 parts of n-octylmercaptan in the reaction vessel for fifteenminutes, and heating and stirring for 1.5 hours after it was added.Subsequently, 10 parts of methyl methacrylate were added for tenminutes, and were heated and stirred for two hours after they wereadded, and then the polymerization reaction was completed, followed bycooling to obtain a latex of copolymer (A). Subsequently, a driedproduct of copolymer (A) was obtained for a part of the obtained latexin the same manner as Example 1.

The mean weight molecular weight (Mw) of the obtained copolymer (A) was730,000 and the molecular weight distribution was 2.7.

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 150parts of ion-exchanged water, 1.5 parts of sodium dioctylsulfosuccinate, 0.3 parts of potassium persulfate, 10 parts of methylmethacrylate and 0.1 parts of n-octylmercaptan, and then the air in thevessel was replaced with nitrogen again, followed by heating thereaction vessel to 65° C. under stirring, and heating and stirring for1.5 hours. Subsequently, a mixture of 36 parts of styrene, 24 parts ofn-butyl acrylate and 1.0 parts of n-octylmercaptan was added therein forninety minutes, and was heated and stirred for two hours after themixture was added. Thereafter, 30 parts of methyl methacrylate and 0.1parts of n-octylmercaptan were added in this reaction system for 45minutes, and were heated and stirred for two hours after they wereadded, followed by completing the polymerization reaction and cooling toobtain a latex of copolymer (B). Subsequently, a dried product ofcopolymer (B) was obtained for a part of the obtained latex in the samemanner as Example 1.

The mean weight molecular weight (Mw) of the obtained copolymer (B) was70,000.

Latex blending of the copolymer (A) and (B) was carried out in the samemanner as Example1. Subsequently,the obtained latex mixture wasprocessed in the same manner as Example 1 to obtain a powdered copolymermixture. The mean weight molecular weight (Mw) of the obtained copolymerwas 700,000 the molecular weight distribution (Mw/Mn) was 2.9.

EXAMPLE 4

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 150parts of ion-exchanged water, 1.5 parts of sodium dioctylsulfosuccinate, 0.15 parts of potassium persulfate, 40 parts of methylmethacrylate, 6 parts of n-butyl acrylate and 0.0035 parts ofn-octylmercaptan, and then the air in the vessel was replaced withnitrogen again, followed by heating the reaction vessel to 65° C. understirring, and heating and stirring for two hours, followed by adding amixture of 40 parts of methyl methacrylate and 14 parts of n-butylacrylate in the reaction vessel for sixty minutes, and heating andstirring for three hours after it was added, followed by completing thepolymerization reaction, and cooling to obtain a latex of copolymer (A).Subsequently, a dried product of copolymer (A) was obtained for a partof the obtained latex in the same manner as Example 1.

The mean weight molecular weight (Mw) of the obtained copolymer (A) was1,600,000 and the molecular weight distribution was 2.8.

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 150parts of ion-exchanged water, 1.2 parts of sodium dioctylsulfosuccinate, 0.15 parts of potassium persulfate, 40 parts of styrene, 30parts of n-butyl acrylate and 0.9 parts of n-octylmercaptan, and thenthe air in the vessel was replaced with nitrogen again, followed byheating the reaction vessel to 65° C. under stirring, and heating andstirring for two hours, followed by adding a mixture of 30 parts ofmethyl methacrylate and 0.03 parts of n-octylmercaptan in the reactionvessel for 35 minutes, and heating and stirring for three hours after itwas added, followed by completing the polymerization reaction, andcooling to obtain a latex of copolymer (B). Subsequently, a driedproduct of copolymer (B) was obtained for a part of the obtained latexin the same manner as Example 1.

The mean weight molecular weight of the obtained copolymer (B) was90,000.

Latex blending of the copolymer (A) and (B) was carried out in the samemanner as Example 1. Subsequently, the obtained latex mixture wasprocessed in the same manner as Example 1 to obtain a powdered copolymermixture. The mean weight molecular weight (MW) of the obtained copolymerwas 1.480,000 the molecular weight distribution (Mw/Mn) was 2.8.

EXAMPLE 5

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 230parts of ion-exchanged water, 1.0 parts of sodium dioctylsulfosuccinate, 0.15 parts of potassium persulfate, 80 parts of methylmethacrylate, 18 parts of n-butyl acrylate, 2 parts of styrene and0.0185 parts of n-octylmercaptan, and then the air in the vessel wasreplaced with nitrogen again, followed by heating the reaction vessel to65° C. under stirring, and heating and stirring for two hours. followedby completing the polymerization reaction, and cooling to obtain a latexof copolymer (A). Subsequently, a dried product of copolymer (A) wasobtained for a part of the obtained latex in the same manner as Example1.

The mean weight molecular weight (Mw) of the obtained copolymer (A) was900,000 and the molecular weight distribution (Mw/Mn) was 2.1.

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 260parts of ion-exchanged water, 1.5 parts of sodium dioctylsulfosuccinate, 0.2 parts of potassium persulfate, 30 parts of methylmethacrylate and 0.03 parts of n-octylmercaptan, and then the air in thevessel was replaced with nitrogen again, followed by heating thereaction vessel to 65° C. under stirring, and heating and stirring fortwo hours. Subsequently, a mixture of 20 parts of styrene, 30 parts ofn-butyl acrylate and 0.5 parts of n-octylmercaptan was added therein forone hour, and was stirred for two hours after the mixture was added.Thereafter, a mixture of 20 parts of methyl methacrylate and 0.05 partsof n-octylmercaptan was added in this reaction system for thirtyminutes, and was heated and stirred for two hours, followed bycompleting the polymerization reaction and cooling to obtain a latex ofcopolymer (B). Subsequently, a dried product of copolymer (B) wasobtained for a part of the obtained latex in the same manner as Example1.

The mean weight molecular weight (Mw) of the obtained copolymer (B) was190.000.

Latex blending of the copolymer (A) and (B) was carried out in the samemanner as Example 1. Subsequently the obtained latex mixture wasprocessed in the same manner as Example 1 to obtain a powdered copolymermixture. The mean weight molecular weight (Mw) of the obtained copolymerwas 830,000 the molecular weight distribution (Mw/Mn) was 2.8.

Comparative Example 1

Evaluations of molding were made without adding the copolymer mixture tothe vinyl chloride based resin composition.

Comparative Example 2

For the copolymer (A), a latex was prepared in the same manner asExample 1 except that n-octylmercaptan in Example 1 was not used.Subsequently, a dried product of copolymer (A) was obtained for a partof the obtained latex in the same manner as Example 1.

The mean weight molecular weight of the obtained copolymer (A) was3,000,000 and the molecular weight distribution was 3.7.

For the copolymer (B), a latex was prepared in the same manner asExample 1.

Latex blending of the copolymer (A) and (B) was carried out in the samemanner as Example 1. Subsequently,the obtained latex mixture wasprocessed in the same manner as Example 1 to obtain a powdered copolymermixture. The mean weight molecular weight (Mw) of the obtained copolymerwas 2,910,000 the molecular weight distribution (Mw/Mn) was 3.4.

Comparative Example 3

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 150parts of ion-exchanged water, 1.5 parts of sodium dioctylsulfosuccinate, 0.2 parts of potassium persulfate, 85 parts of methylmethacrylate and 0.025 parts of n-octylmercaptan, and then the air inthe vessel was replaced with nitrogen, followed by heating the reactionvessel to 65° C. under stirring, and heating and stirring for threehours, followed by adding a mixture of 2.5 parts of methyl methacrylate,2.5 parts of n-butyl acrylate and 0.5 parts of n-octylmercaptan in thereaction vessel for fifteen minutes, and heating and stirring for 1.5hours after it was added. Subsequently, 10 parts of methyl methacrylatewere added for ten minutes, and were heated and stirred for two hoursafter they were added, followed by completing the polymerizationreaction and cooling to obtain a latex of copolymer (A). Subsequently, adried product of copolymer (A) was obtained for a part of the obtainedlatex in the same manner as Example 1.

The mean weight molecular weight (Mw) of the obtained copolymer (A) was790,000 and the molecular weight distribution was 2.7.

For the copolymer (B), a latex was prepared in the same manner asExample 1.

Latex blending of the copolymer (A) and (B) was carried out in the samemanner as Example 1. Subsequently, the obtained latex mixture wasprocessed in the same manner as Example 1 to obtain a powdered copolymermixture. The mean weight molecular weight (Mw) of the obtained copolymerwas 760,000 the molecular weight distribution (Mw/Mn) was 2.9.

Comparative Example 4

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 150parts of ion-exchanged water, 1.5 parts of sodium dioctylsulfosuccinate, 0.2 parts of potassium persulfate, 50 parts of methylmethacrylate, 30 parts of n-butyl acrylate and 0.009 parts ofn-octylmercaptan, and then the air in the vessel was replaced withnitrogen, followed by heating the reaction vessel to 65° C. understirring, and heating and stirring for three hours, followed by adding amixture of 20 parts of methyl methacrylate and 0.06 parts ofn-octylmercaptan in the reaction vessel for thirty minutes, and heatingand stirring for two hours after it was added, followed by completingthe polymerization reaction, and cooling to obtain a latex of copolymer(A). Subsequently, a dried product of copolymer (A) was obtained for apart of the obtained latex in the same manner as Example 1.

The mean weight molecular weight (Mw) of the obtained copolymer (A) was270, 000and the molecular weight distribution was 2.6.

For the copolymer (B), a latex was prepared in the same manner asExample 1.

Latex blending of the copolymer (A) and (B) was carried out in the samemanner as Example 1. Subsequently, the obtained latex mixture wasprocessed in the same manner as Example 1 to obtain a powdered copolymermixture. The mean weight molecular weight (Mw) of the obtained copolymerwas 220,000 the molecular weight distribution (Mw/Mn) was 2.8.

Comparative Example 5

A latex was prepared in the same manner as Example 1 except that theamounts of methyl methacrylate and n-butyl acrylate were changed to 80parts and 20 parts, respectively. Subsequently, a dried product ofcopolymer (A) was obtained for a part of the obtained latex in the samemanner as Example 1.

The mean weight molecular weight of the obtained copolymer (A) was1,060,000 and the molecular weight distribution (Mw/Mn) was 2.3.

A latex was prepared in the same manner as Example 2 except thatn-octylmercaptan of the copolymer (B) in Example 2 was changed to 0.05parts. Subsequently a dried product of copolymer (B) was obtained for apart of the obtained latex in the same manner as Example 1.

The mean weight molecular weight (Mw) of the obtained copolymer (B) was810,000.

Latex blending of the copolymer (A) and (B) was carried out in the samemanner as Example 1. Subsequently, the obtained latex mixture wasprocessed in the same manner as Example 1 to obtain a powdered copolymermixture. The mean weight molecular weight (Mw) of the obtained copolymerwas 220,000 the molecular weight distribution (Mw/Mn) was 2.5.

Comparative Example 6

Latexes of copolymer (A) and copolymer (B) were prepared in the samemanner as Example 1.

Latex blending of the copolymer (A) and (B) was carried out in the samemanner as Example 1 except that 200 parts of copolymer (B) were used forlatex blending as a solid matter. Subsequently, the obtained latexmixture was processed in the same manner as Example 1 to obtain apowdered copolymer mixture. The mean weight molecular weight (Mw) of theobtained copolymer was 740,000 the molecular weight distribution (Mw/Mn)was 3.8.

Comparative Example 7

A latex of copolymer (A) was prepared in the manner as Example 1. Latexblending of copolymer (A) and copolymer (B) was not carried out.

Comparative Example 8

A latex of copolymer (A) was prepared in the same manner as Example 1.

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 150parts of ion-exchanged water, 1.0 parts of sodium dioctylsulfosuccinate, 0.15 parts of potassium persulfate, 20 parts of styrene, 60parts of n-butyl acrylate and 0.09 parts of n-octylmercaptan, and thenthe air in the vessel was replaced with nitrogen again, followed byheating the reaction vessel to 65° C. under stirring, and heating andstirring for two hours, followed by adding 20 parts of methylmethacrylate in the reaction vessel for thirty minutes and heating andstirring for three hours after they were added, followed by completingthe polymerization reaction, and cooling to obtain a latex of copolymer(B). Subsequently, a dried product of copolymer (B) was obtained for apart of the obtained latex in the same manner as Example 1.

The mean weight molecular weight of the obtained copolymer (B) was230,000.

Latex blending of the copolymer (A) and (B) was carried out in the samemanner as Example 1. Subsequently, the obtained latex mixture wasprocessed in the same manner as Example 1 to obtain a powdered copolymermixture. The mean weight molecular weight (Mw) of the obtained copolymerwas 1,060,000 the molecular weight distribution (Mw/Mn) was 2.4.

Comparative Example 9

Air in a reaction vessel provided with a stirrer and a reflux cooler wasreplaced with nitrogen, followed by placing therein a mixture of 150parts of ion-exchanged water, 1.5 parts of sodium dioctylsulfo succinate0.15 parts of potassium persulfate, 40 parts of methyl methacrylate, 6parts of n-butyl acrylate and 0.0035 parts of n-octylmercaptan, and thenthe air in the vessel was replaced with nitrogen again, followed byheating the reaction vessel to 65° C. under stirring, and heating andstirring for two hours, followed by adding a mixture of 40 parts ofmethyl methacrylate and 14 parts of n-butyl acrylate in the reactionvessel for thirty minutes, and heating and stirring for three hoursafter it was added, followed by completing the polymerization reaction,and cooling to obtain a latex of copolymer (A). Subsequently, a driedproduct of copolymer (A) was obtained for a part of the obtained latexin the same manner as Example 1.

The mean weight molecular weight (Mw) of the obtained copolymer (A) was1,750,000 and the molecular weight distribution was 3.6.

A latex of copolymer (B) was prepared in the same manner as Example 1.

Latex blending of the copolymer (A) and (B) was carried out in the samemanner as Example 1. Subsequently, the obtained latex mixture wasprocessed in the same manner as Example 1 to obtain a powdered copolymermixture. The mean weight molecular weight (Mw) of the obtained copolymerwas 1,720,000 the molecular weight distribution (Mw/Mn) was 3.4.

Comparative Example 10

Latexes of copolymer (A) and (B) were prepared in the same manner asExample 1, and latex blending was carried out in the same manner asExample 1. Subsequently, the obtained latex mixture was processed in thesame manner as Example 1 to obtain a powdered copolymer mixture. 0.1parts of the obtained copolymer mixture were added and blended in thevinyl chloride based resin composition.

Comparative Example 11

Latexes of copolymer (A) and (B) were prepared in the same manner asExample 1, and latex blending was carried out in the same manner asExample 1. Subsequently, the obtained latex mixture was processed in thesame manner as Example 1 to obtain a powdered copolymer mixture. 30parts of the obtained copolymer mixture were added and blended in thevinyl chloride based resin composition.

TABLE 1 Amount of added Composition of copolymer mixture copolymermixture in Copolymer Copolymer vinyl chloride based Roll (A) (B) resincomposition Releasability Gelation time (parts) (parts) (parts)(minutes) Flow marks Air marks (minutes) Ungelled products Example 1 10010 3 15.5 ∘ ∘ 1.3 ∘ Example 2 100 10 3 14.0 ∘ ∘ 1.3 ∘ Example 3 100 10 314.5 ∘ ∘ 1.2 ∘ Example 4 100 10 3 14.0 ∘ ∘ 1.0 ∘ Example 5 100 10 3 15.0∘ ∘ 1.0 ∘ Comparative — — —  2.5 ∘ x 2.5 x Example 1 Comparative 100 103 14.5 x ∘ 1.2 ∘ Example 2 Comparative 100 10 3 13.0 ∘ ∘ 1.7 x Example 3Comparative 100 10 3 14.0 ∘ x 1.4 Δ Example 4 Comparative 100 10 3  9.5Δ ∘ 1.3 ∘ Example 5 Comparative 100 200  3 Over 30.0 ∘ x 8.5 x Example 6Comparative 100 — 3  3.5 ∘ ∘ 1.3 ∘ Example 7 Comparative 100 10 3 12.5 ∘x 5.2 Δ Example 8 Comparative 100 10 3 13.5 x ∘ 1.5 ∘ Example 9Comparative 100 10 0.1  3.0 ∘ ∘ 2.0 x Example 10 Comparative 100 10 3021.0 x ∘ 0.5 ∘ Example 11

As described above, the processing aid for vinyl chloride based resinand the vinyl chloride based resin composition using the aid improveprocessability of vinyl chloride based resin, eliminate flow marksgenerated on a calender-molded sheet or film or an extrusion-moldedsheet or film, reduce exudation, and have an excellent effect onreleasability of the calender-molded sheet, and their industrial valueis extremely high.

What is claimed is:
 1. A processing aid comprising: a copolymer (A)whose mean weight molecular weight (Mw) measured with gel permeationchromatography is in the range of from 700,000 to 2,000,000, andmolecular weight distribution (Mw/Mn) is 3.0 or smaller, which isobtained by copolymerizing a monomer mixture comprising 70 to 90% byweight of methyl methacrylate, 10 to 30% by weight of acrylate ormethacrylate other than methyl methacrylate, and 3% by weight or less ofa different type of monomer capable of being copolymerized with thosemonomers; and a copolymer (B) whose mean weight molecular weight (Mw)measured with gel permeation chromatography is in the range of from10,000 to 500,000, which is obtained by copolymerizing a monomer mixturecomprising at least 30 to 50% by weight of methyl methacrylate, amonomer other than a polyfunctional monomer and having as constitutionalunits at least one type other than methyl methacrylate, and 2% by weightor less of polyfunctional monomers, wherein copolymer (A) and copolymer(B) are present in a ratio of 100 parts by weight of copolymer (A) to0.5-100 parts by weight of copolymer (B).
 2. A vinyl chloride basedresin composition comprising 100 parts by weight of vinyl chloride basedresin and 0.2 to 20 parts by weight of the processing aid as set forthin claim
 1. 3. A calender molded product obtained with the processingaid as set forth in claim
 1. 4. A calender molded product obtained bycalender molding the vinyl chloride based resin composition as set forthin claim
 2. 5. A method of producing moldings comprising calendermolding the vinyl chloride resin composition as set forth in claim
 2. 6.The processing aid as set forth in claim 1, wherein themethylmethacrylate in the monomer mixture of copolymer (A) is present inan amount of 80-90% by weight.
 7. The processing aid as set forth inclaim 1, wherein the monomer other than a polyfunctional monomer in themonomer mixture of copolymer (B) is present in an amount of 45-70% byweight.
 8. The processing aid as set forth in claim 7, wherein saidamount is 50-60% by weight.
 9. The vinyl chloride based resincomposition as set forth in claim 2, wherein the vinyl chloride basedresin has a mean degree of polymerization of from 300-5,000.
 10. Thevinyl chloride based resin composition as set forth in claim 9, whereinsaid mean degree of polymerization is 500-3,000.
 11. The calender moldedproduct as set forth in claim 3, wherein the methylmethacrylate in themonomer mixture of copolymer (A) is present in an amount of 80-90% byweight.
 12. The calender molded product as set forth in claim 3, whereinthe monomer other than a polyfunctional monomer in the monomer mixtureof copolymer (B) is present in an amount of 45-70% by weight.
 13. Thecalender molded product as set forth in claim 12, wherein said amount is50-60% by weight.
 14. The calender molded product as set forth in claim4, wherein the methylmethacrylate in the monomer mixture of copolymer(A) is present in an amount of 80-90% by weight.
 15. The calender moldedproduct as set forth in claim 4, wherein the monomer other than apolyfunctional monomer in the monomer mixture of copolymer (B) ispresent in an amount of 45-70% by weight.
 16. The calender moldedproduct as set forth in claim 15, wherein said amount is 50-60% byweight.
 17. The method as set forth in claim 5, wherein the vinylchloride based resin has a mean degree of polymerization of from300-5,000.
 18. The method as set forth in claim 5, wherein the vinylchloride based resin has a mean degree of polymerization of from500-3,000.